METALLIC GLASS FASTENING SCREW

摘要

PROBLEM TO BE SOLVED: To provide a metallic glass fastening screw which is high in strength and achieves fastening of high reliability in a wide field including a lightweight member by imparting a hardly loosened property to the screw itself.

SOLUTION: In machining a thread ridge and a thread groove of the screw 7, bulk metallic glass formed of an amorphous substance is molded by rolling below the glass transition temperature of bulk metallic glass which is a workpiece. The bulk metallic glass has a characteristic of introducing plastic strain to improve ductility of a portion including a slip band by plastic working such as rolling. This characteristic is effectively utilized to satisfy a relationship of d>0.022×D, wherein a depth from the bottom of the thread groove of a region into which plastic strain is introduced by rolling is set to d and a screw outer diameter is set to D to relieve the stress concentration of tensile stress generated in the region of the bottom of the thread groove by tensile force (axial force) applied to the screw 7 when fastened.

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